Until recently, being photogenic has been one of those happy accidents of the gene pool. Now all it really takes is a smart phone.

Thanks to the ever-increasing sophistication of smart-phone photography apps, users can shoot images, alter them with a widening array of visual effects, and rapidly share the results over social networks and e-mail.

"It can be very forgiving," says Erin Hagstrom, who frequently uses the Instagram app as part of her job with the San Francisco apparel company ModCloth and also on her own style blog, Cali Vintage.

In fact, Instagram, a San Francisco photo-sharing app known for revamping iPhone images with retro details, has become a common obsession among fashion industry insiders and style bloggers.

"It makes photos prettier. I always laugh, because I take some crappy photo and put on these filters and it looks so much better. I'm amazed at what it can do," says Laura Ellner, a marketing associate for San Francisco startup Shop It To Me, who sends Instagram images out to company fans as part of her role there and also uses them for her own style blog, OnTheRacks.

Instagram the trend leader

With nearly 10 million users and a new version out late last month offering updated features such as image filtering before a picture is taken and high-resolution versions of shots, Instagram is, for the moment at least, the undisputed darling of the iPhone-wielding fashion set. Burberry, Kate Spade and Bergdorf Goodman are using it, as are Urban Outfitters and Banana Republic.

And while more brands are catching on, the app's founders have had fashion in mind all along.

"When we were initially pitching investors, one of the slides in my pitch deck had a slide of Banana Republic," recalls Instagram co-founder Kevin Systrom.

Though Systrom says the company does not work in an official capacity with fashion brands, he notes an uptick by fashion brands and others interested in fashion.

"Obviously the rush started with Fashion Week, but even before that, we've seen even more and more people signing up," he says.

In August, Banana Republic began using the app during launch events for its Mad Men collection, inspired by the AMC television show.

"It aligns perfectly with our collection, which was basically about taking a classic and reinterpreting it for modern times," explains Alejandro Alvarez, Banana Republic's director of marketing.

Behind-the-scenes images of the photo shoot for the collection were shared with fans and followers. More recently, shots of a fishtail braid, happy-hour drinks and a worker perfecting a sample garment were among Banana Republic's images.

ModCloth, which started sharing Instagram images with its fans in earnest this August, also uses the app for behind-the-scenes shots. Fashion shows, company photo shoots, parties, staffers' outfits and office dogs make frequent appearances in the company's image feed.

"The whole behind-the-scenes thing is really appealing to people, particularly what we can show people about the culture in our office," says ModCloth's Hagstrom.

And while product shots do appear among the images shared by most fashion companies, they do not dominate, at least for now. There's a good reason for that.

"It's not the best product shot. It's not the best platform to sell a product," says Alvarez.

Slew of similar apps available

Instagram may be the most popular choice among fashion bloggers and brands, but it's hardly the only one. Hipstamatic, also based in San Francisco, counts about 4 million users, who access the iPhone app for a camera resembling an old-fashioned toy and limited-edition add-on accessories that include visual-effects-laden HipstaPaks, lenses and film.

In February, Hipstamatic launched a temporarily available lens for New York Fashion Week and collaborated with fashion photographers Chiun-Kai Shih and Ben Watts. Used with the app's camera, it was designed to mimic the experience of changing out camera lenses for different effects.

For those who enjoy combining cocktails and cameras, one of the company's most recent releases is a HipstaPak designed with watering holes in mind.

"We've made it so you could take a really good bar photo," says Mario Estrada of Hipstamatic's parent company, Synthetic.

MoreBeaute2, a reported favorite of interior designer Kelly Wearstler, lets you smooth, tone and brighten skin before you share an image over social networks. For Android phones, there's Snaptastic, FxCamera, Retro Camera, Vignette, Beauty Camera and Pixlr-o-Matic, to name a few. An Android version of Instagram is reportedly due out in coming months.